0000000000769855
AUTHOR
K. Książek
The influence of mechanical damaging on the lifetime of positrons In ultrahigh-molecular polyethylene
We study the influence of damaging of ultrahigh-molecular polyethylene [(PE-UHMW) Chirulen®1120] applied, among other materials, in the production of hip endoprostheses on the spectra of positrons lifetime in this material. Polyethylene samples were damaged by the impacts, rolling friction, and collisions with metal balls in a planetary mill. The changes in the parameters of the spectra of positrons lifetime related to the annihilation of orthopositronium (o-Ps) were analyzed depending on the mechanical energy transferred to the sample. On the basis of the Eldrup–Tao model, the changes in the radii of voids in which positroniums are formed and annihilated and the changes in the degree of fi…
Relations between the cohesive energy, atomic volume, bulk modulus and sound velocity in metals
By analysing the experimental data available in the literature, it has been found that the bulk modulus B of metals is proportional to the cohesive energy density Ec/V. For metals which start to melt having the close packed structure A1 or A3 the proportionality factor in the forementioned correlation is distinctly greater than that for metals melting from the A2 type structure. The existence of the correlation between the bulk modulus and the cohesive energy density leads to another, hitherto unrevealed correlation between the sound velocity, cohesive energy and the molar mass of metals: u2 ~ Ec/μ.
Investigation of the effect of intensive milling in a planetary ball mill on the thermal decomposition of basic nickel carbonate
The kinetics of thermal decomposition of basic nickel carbonate NiCO3Ni?(OH)2?nH2O and the effect of intensive milling in a planetary ball mill on its parameters, have been investigated. The values of the reaction heat and of the activation energy of thermal decomposition have been determined. Investigations of the thermal decomposition of the products of ball milling of investigated compound revealed a distinct effect of milling on the reaction temperature and heat consumed during the thermal decomposition of investigated compound.